hello guys,

yesterday i went to the field to sort of maiden a 46 size graupner piper cub j-3 which i bought from a guy who crashed it and needed the nose to be rebuilt. a friend helped me with the rebuilt and we (mostly he) made a pretty good job.

on take-off the plane did not track straight but instead wanted to go left. i applied right rudder but when it took-off it violently banked right and hit the ground with the right wingpanel. minor damage, but the question remains. why it behaves like this and what can i do to correct the problem.

BTW i also had a balance problem. with a heavier engine than normal the plane is still way too tail heavy. the manual states that the CG is 70mm aft the LE. for that setting it needs 120 grams (4 oz) of lead in the firewall.

best regards
red

ok come now. everybody knows everything about cubs but when you ask a specific question nobody knows nothing .shame guys. there must be a lot of you who own cubs and fly them without problems.

Red, I think you answered your own question, if the airplane is tailheavy it will do that! Buf first things first, if didn't track straight, that's normal for a taildragger like a Cub because of the engine torque, but the way to apply rudder is to do it gradually as you need it to keep it straight on the runway and not overapply rudder. I suspect that maybe after take off you held the rudder for too long and that coupled with the tailheavy attitude caused the plane to bank right and hit the ground. You should make sure that the airplane is properly balanced at the correct CG (extremely important!). For better tracking on the ground, I recommend putting a little tow in on the wheels. Try it again and remember apply rudder gradually, and as soon as it takes off get off the rudder and also climb gradually. Hope this helps!

i know how to fly a tail dragger. all my planes are tail draggers. and it was corectly balanced with 120 grams of lead in the nose. so i say it wasn't the pilot either the CG.

BTW, yesterday i added toe-in to the landing gear and went flying. tracked straighe, got airborne about 3 feet and than violently banked right and smashed into the ground. fuse totaled, wing without scratches. could be repaired but i just don't want to.

I had a smaller Cub (130cm) and the same experiences. I used an electric motor combination which runs perfectly in another plane with nearly the same dimensions. But the Cub had only one flight which lasted longer than 10sec. - of course it ended with a crash.

RK